Entanglement and Quantum Computation

Abstract The phenomenon of quantum entanglement is perhaps the most enigmatic feature of the formalism of quantum theory. It underlies many of the most curious and controversial aspects of the quantum mechanical description of the world. Penrose (1994) gives a delightful and accessible account of entanglement illustrated by some of its extraordinary manifestations. Many of the best known features depend on issues of non-locality. These include the seminal work of Einstein, Podolsky and Rosen (1935), Bell’s work (1964) on the EPR singlet state, properties of the GHZ state (Greenberger et al. 1989; Mermin 1990) and Penrose’s dodecahedra (Penrose 1994). In this paper we describe a new feature of entanglement which is entirely independent of the auxiliary notion of non-locality.